The Hominoids were quadrupeds. They walked on all four limbs, but, their forelimbs were flexible. The Hominids gradually adapted an upright posture. Hominines further adapted to bipedalism. The skeletal structure and the muscles also adjusted over a period of time to the upright posture and the bipedal motion, which freed the forelimbs.

The forelimbs developed precision grip and power grip and evolved into hands. This greatly helped in hunting and defending from predators as hands could be used to make tools and also use them. Walking on two legs also provided a greater long-distance vision and helped them to cover long distances without spending much energy.

The use of tools is not confined to only humans. For e.g. some monkeys and apes use stones as tools to break nuts. But use of tools by humans is far more advanced compared to the monkeys and apes. Wood, bones, and stones were used to make tools. They were mainly used for hunting or defending from predators. The use of stone tools is studied as the Stone Age in history.

The making and use of stones tools were responsible to the evolution of forelimbs into hands and also the growth in brain size. The oldest known stone tools are the ‘Oldowan stone tools’ from Ethiopia which are dated to a period 2.6 million years ago. The skill and advancement in making stone tools have made historians to classify the Stone Age as Paleolithic, Mesolithic and Neolithic stone ages.

In the course of time, humans began to produce metals from ores and make copper, bronze and iron tools which are studied in history as the respective metal ages. The Australopithecus species is said to have first used the naturally available stones as tools. But, the making of stone tools from naturally available stones and using them is positively identified to have begun with Homo habilis.